The liver microsomal vitamin K-dependent carboxylase converts percursor forms of plasma clotting factors to the active enzymes through the conversion of specific glutamyl residues of these precursors to gamma-carboxyglutamyl residues of the finished proteins. The actions of this enzyme will be studied through the synthesis of low molecular weight peptides which are substrates for this enzyme. These peptides will be used to determine the substrate specificity of the enzyme, and to develop inhibitors of the glutamyl binding site(s) of the enzyme.